Defines the type of physical interface used by a Driver. Possible values are the following:

•N or None: Does not use a physical interface, that is, a Driver must provide a customized interface

•S or Serial: Uses a local serial port (COMn)

•M or Modem: Uses a local modem, internal or external, accessed via TAPI (Telephony Application Programming Interface)

•E or Ethernet: Uses a TCP/IP or UDP/IP socket

•R or RAS: Uses a RAS (Remote Access Server) Interface. A Driver connects to a RAS device using the Ethernet Interface and then sends an AT (dial) command